So, is it smarter and cheaper for me to buy this rim and have my LBS lace it up to my hub? Any idea on what your local LBS charges for such a procedure?

However, you should buy another hub so youll have two complete rear wheels instead of a rear wheel and a hub and useless spokes. You cant reuse the spokes as the rims are different depths and such. Besides, the cost of labor and new spokes will be the cost of your new back wheel anyway.